/*
 * The Apache Software License, Version 1.1
 *
 * Copyright (c) 2000,2002 The Apache Software Foundation.  All rights
 * reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 *
 * 3. The end-user documentation included with the redistribution, if
 *    any, must include the following acknowlegement:
 *       "This product includes software developed by the
 *        Apache Software Foundation (http://www.apache.org/)."
 *    Alternately, this acknowlegement may appear in the software itself,
 *    if and wherever such third-party acknowlegements normally appear.
 *
 * 4. The names "Ant" and "Apache Software
 *    Foundation" must not be used to endorse or promote products derived
 *    from this software without prior written permission. For written
 *    permission, please contact apache@apache.org.
 *
 * 5. Products derived from this software may not be called "Apache"
 *    nor may "Apache" appear in their names without prior written
 *    permission of the Apache Group.
 *
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED.  IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR
 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
 * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 * ====================================================================
 *
 * This software consists of voluntary contributions made by many
 * individuals on behalf of the Apache Software Foundation.  For more
 * information on the Apache Software Foundation, please see
 * <http://www.apache.org/>.
 */

package com.java.mc.utils;

/**
 * Stores the location of a piece of text within a file (file name, line number
 * and column number). Note that the column number is currently ignored.
 */
public class Location {

	/** Name of the file. */
	private String fileName;
	/** Line number within the file. */
	private int lineNumber;
	/** Column number within the file. */
	private int columnNumber;

	/** Location to use when one is needed but no information is available */
	public static final Location UNKNOWN_LOCATION = new Location();

	/**
	 * Creates an "unknown" location.
	 */
	private Location() {
		this(null, 0, 0);
	}

	/**
	 * Creates a location consisting of a file name but no line number or column
	 * number.
	 * 
	 * @param fileName
	 *            The name of the file. May be <code>null</code>, in which case
	 *            the location is equivalent to {@link #UNKNOWN_LOCATION
	 *            UNKNOWN_LOCATION}.
	 */
	public Location(String fileName) {
		this(fileName, 0, 0);
	}

	/**
	 * Creates a location consisting of a file name, line number and column
	 * number.
	 * 
	 * @param fileName
	 *            The name of the file. May be <code>null</code>, in which case
	 *            the location is equivalent to {@link #UNKNOWN_LOCATION
	 *            UNKNOWN_LOCATION}.
	 * 
	 * @param lineNumber
	 *            Line number within the file. Use 0 for unknown positions
	 *            within a file.
	 * @param columnNumber
	 *            Column number within the line.
	 */
	public Location(String fileName, int lineNumber, int columnNumber) {
		this.fileName = fileName;
		this.lineNumber = lineNumber;
		this.columnNumber = columnNumber;
	}

	/**
	 * Returns the file name, line number, a colon and a trailing space. An
	 * error message can be appended easily. For unknown locations, an empty
	 * string is returned.
	 * 
	 * @return a String of the form <code>"fileName: lineNumber: "</code> if
	 *         both file name and line number are known,
	 *         <code>"fileName: "</code> if only the file name is known, and the
	 *         empty string for unknown locations.
	 */
	public String toString() {
		StringBuffer buf = new StringBuffer();

		if (fileName != null) {
			buf.append(fileName);

			if (lineNumber != 0) {
				buf.append(":");
				buf.append(lineNumber);
			}

			buf.append(": ");
		}

		return buf.toString();
	}
}